The present invention relates to the creation of a shock wave and, more specifically, to a novel, reusable, and economical shock tube design.
Shock tubes are used to generate and study shock waves in applications such as supersonic aerodynamic research. For example, U.S. Pat. No. 5,511,978, the disclosure of which is incorporated herein by reference, teaches an explosion simulator device that utilizes a shock tube to produce a shock wave in the surrounding atmosphere. The shock tube illustrated therein consists of an open-mouthed tube connected to a compressed gas reservoir. The opening between the compressed gas reservoir and the shock tube is blocked by a frangible diaphragm. The frangible diaphragm may be broken by increasing the gas pressure to the bursting pressure of the diaphragm or by physically piercing the diaphragm by some external means. A shock wave is released from the shock tube when the diaphragm is burst. Unfortunately, once the diaphragm is burst and the shock wave released, the diaphragm must be replaced to reuse the device.
The above-described part replacement requirement represents a significant limitation on the utility of the explosion simulator taught in the ""978 patent. Accordingly, there is a need for a shock wave simulator that is capable of producing repeated shock waves without the need for replacement parts.
This need is met by the present invention wherein a shock wave generator having utility in a variety of applications is provided. The shock wave generator includes a high speed gas valve capable of repeatedly allowing pressurization of a compressed gas reservoir and permitting rapid release of the compressed gas into a shock tube.
In accordance with one embodiment of the present invention, a shock wave generator is provided comprising a compressed gas reservoir, a high speed valve assembly, and a shock tube. The high speed valve assembly is arranged to open and close selectively a gas passage extending from the compressed gas reservoir to the shock tube. The high speed valve assembly comprises a valve sleeve, a valve seat, and a valve sleeve driving assembly. The valve sleeve is arranged to extend across the gas passage between a first side of the gas passage and a second side of the gas passage. The valve seat is arranged on the second side of the gas passage and is positioned to receive the valve sleeve upon extension of the valve sleeve across the gas passage. The valve sleeve driving assembly is arranged to cause extension and retraction of the valve sleeve across the gas passage.
The valve sleeve preferably includes a valve sleeve flange arranged on a leading edge of the valve sleeve and the compressed gas reservoir is preferably arranged such that the compressed gas imparts uniform compressive loading upon the valve sleeve. More specifically, the valve sleeve may define a circular cross section and an epicentral valve sleeve axis and the gas passage may be arranged annularly about the circular valve sleeve. The valve sleeve flange and the valve seat are then preferably arranged such that pressurized gas from the compressed gas reservoir forcibly urges the sleeve flange against the valve seat.
The compressed gas reservoir, the gas passage, and the shock tube may be arranged to define a gas flow path that converges continuously from a first circular cross section to a smaller second circular cross section. The continuously converging gas flow path may converge while extending in a single direction or may define a reverse flow configuration.
The valve sleeve driving assembly may comprise a linear electric motor. The linear electric motor typically defines a motive axis that is parallel to the valve sleeve axis. Preferably, the linear electric motor comprises an armature and a field coil and the valve sleeve is physically coupled to the armature.
The valve sleeve driving assembly preferably includes a capacitive discharge power source arranged to enable rapid retraction of the valve sleeve across the gas passage. The valve sleeve driving assembly may further include an assist power source arranged to prevent recoil of the valve sleeve upon retraction of the valve sleeve and enable extension of the valve sleeve across the gas passage.
In accordance with another embodiment of the present invention, a shock wave generator is provided comprising a compressed gas reservoir, a high speed valve assembly, and a shock tube. The high speed valve assembly is arranged to selectively seal compressed gas within the compressed gas reservoir and selectively release compressed gas from the compressed gas reservoir into the shock tube. The high speed valve assembly comprises a valve sleeve, a valve seat, and a valve sleeve driving assembly. The valve sleeve defines a circular cross section and an epicentral valve sleeve axis and includes a valve sleeve flange arranged on a leading edge thereof. The valve seat is positioned to receive the valve sleeve flange such that pressurized gas from the compressed gas reservoir forcibly urges the valve sleeve flange against the valve seat. The valve sleeve driving assembly is arranged to impart movement to the valve sleeve along the valve sleeve axis. Preferably, the compressed gas reservoir is arranged such that the compressed gas imparts uniform compressive loading upon the valve sleeve.
Accordingly, it is an object of the present invention to provide a shock wave generator having utility in a variety of applications and having the capability of producing repeated shock waves without the need for replacement parts. Other objects of the present invention will be apparent in light of the description of the invention embodied herein.